The primary objective of this investigation is to explore the functional and structural roles of the phosphoinositides in living cells. In order to achieve this goal, we will continue to improve our methodology and develop new techniques for qualitative and quantitative studies of these phospholipids not only in normal tissue but also in certain conditions utilizing agents known to affect the cardiovascular systems, e.g., catecholamines. It is planned to study the subcellular location and the mode of the association of the three phosphoinositides with other cellular components in the heart and kidney in order to gain a better understanding of their structural and functional roles. Phosphoinositides are structurally distinct from other phospholipids in that they have two types of phosphate esters; the monoesterified phosphate and the diesterified phosphate. We propose to initiate metabolic studies on the factors which control the metabolism of the phosphoinositides. It is planned to use isotopic techniques to carry out studies in vitro and in vivo. The labeling of the phosphoinositides and enzyme activity will reflect the metabolic change under various conditions. It is proposed to expand our studies on the subcellular localization and to characterize the enzymes involved in the metabolism of the phosphoinositides. Using the purified enzyme preparations, we will be able to elucidate the mechanism of the metabolic alterations in the presence of various kinds of effectors. Thus, these studies will provide us with a knowledge concerning certain functional roles of the phosphoinositides.